The genetic disorder alpha-thalassemia-1 is found with highest frequency in individuals of southeast Asian ancestry. While the heterozygous form may have no adverse health effects except for slight anemia, the homozygous condition (known as hydrops fetalis) causes fetal death. There is no readily available clinical assay to screen adults for this trait. However, it has been reported that carriers of the alpha-thalassemia-1 gene produce small quantities of the embryonic hemoglobin zeta-chain. The goal of the second phase of this project is to continue development of an enzyme linked immunoassay for zeta-globin chains using the monoclonal antibodies developed in the first phase. The prototype assay will be optimized. Clinical samples will be assayed for zeta-containing hemoglobin by the optimized assay and by HPLC. Hematological characteristics of these samples will be measured. Specific gene deletions of some of the samples will also be determined. These data will be used to demonstrate the usefulness of the assay for screening adult populations for alpha-thalassemia-1. A second potential screening assay for zeta-chain containing red blood cells will be developed. An anti-zeta-chain monoclonal antibody is conjugated to fluorescein. This will be used to label zeta globin chains in prepared red blood cells, for the determination of zeta chain containing cells by flow cytometry.